DESCRIPTION: (Applicant's Abstract) The candidate's goal in this Scientist Development Award (K01) is to foster her development as an independent investigator and to apply the knowledge acquired during this training to the identification of risk and protective factors that predict or mediate substance abuse in high-risk children. Thus, the applicant seeks additional training in drug abuse and addictions, developmental psychopathology, and the technical aspects of longitudinal data analysis. The combination of additional training and supervised research offered by the SDA would enable the candidate to further develop these skills. Since it is believed that neuropsychiatrically affected children of substance abusing parents may represent those at highest risk for later development of drug use disorders, the proposed investigation will be based on subjects who were originally sampled for a family-genetic study of ADHD. Existing data from a prospective, longitudinal family-genetic study of boys with ADHD and non-ADHD controls will be examined. This is a large-scale study of 260 probands and their first-degree relatives. Families in which at least one parent has a drug use disorder will be compared with families where neither parent has a drug use disorder. Hypotheses concerning the interface between developmental psychopathology and drug use disorders will be examined using cross sectional data. These hypotheses will be tested further using longitudinal data and cross-validated using data from an additional ongoing, prospective, longitudinal studies -- a family-genetic study of girls with ADHD.